Cam locks for zipper fasteners



Dec. 23, 1958 o. FIRING ETAL CAM LOCKS FOR ZIPPER FASTENERS Filed April1a, 1956 fig. 7 2,5 20 '25 I nvntofs Usborne Firing Otto J. Huelsterfactor involved.

United States PatentO CAM LOCKS FOR ZIPPER FASTENERS Osborne Firing,Woodbury, and Otto J. Huelster, Plymouth, Conn., assignors to ScovillManufacturing Company, Waterbury, Conn., a corporation of ConnecticutApplication April 18,1956, Serial No. 579,015

3 Claims. (Cl. 24--205.14)

This invention relates to improvements in cam locks for zipper fastenersand to a novel method of making the same.

For reasons well understood in the art, such garments as mens trousersare provided with cam lock sliders as distinguished from other formssuch as the pin lock or automatic lock. Ever since the introduction ofcam lock sliders for trousers many years ago there has been a seriousproblem having to do with what is called in the trade as reversepressing. The condition comes about when a garment is laundered or drycleaned because it may come to the pressing machine'with the pull tablaid backward or in the reverse or unlocking position. The cam or camsthus project upwardly and are subjected to extreme pressure by thepressing machine. This very frequently results in a deformation of thecam itself, or a bending of the bifurcations of the pull tab, so thatwhen the pull is swung to locking position the cam or cams will notengage the fastener elements with sufficient pressure to lock theslider.

Many attempts have been made to solve this problem Fig. 2 is alongitudinal sectional view through the slider showing the pull tab inelement gripping position, with dotted lines indicating the reverseposition.

Figs. 3, 4 and 5 are perspective views of the pull tab showing differentstages in forming the locking cams.

Fig. 6 shows portions of the forming tools for swaging the cam lugs ofthe pull tab as they appear prior to the swaging operation.

Fig. 7 is a similar view showing the tools in final swaging position.

Fig. 8 is a perspective view of one of the die members and swaging toolsin separated relationship, and

Fig. 9 is a perspective view of the pull tab showing the bifurcated endas it appears before the assembly of the slider.

Referring now to the drawings in which like numerals I designate likeparts throughout theseveral views, the

- a pair of parallel slots 14 between which is formed a bail asindicated by several patents in this particular art, but

in actual experience none of them have been wholly satisfactory.

The problem is further intensified because of the cost It isdesirablefor this reason to make the pull tab from a flat strip of metal no widerthan the rectangular handle portion of the tab so that the camsthemselves must be formed from longitudinal extensions of thissame-metal. The necessary height of the cam is substantially more thanthe thickness of the metal itself so that when the cams are formed byfolding over tongues extending from the end of the tab, at least somepart of the cam would be spaced from the body of the pull tab. This isexemplified in Patent No. 2,539,520, granted January 30, 1951. It isalso desirable that the cams have a considerable extent lengthwise ofthe pull tab to avoid too great concentration of force from the pressingmachine- For this reason among others it would not suffice merely tomake a sharp U bend of the tongue with its end against the body of thepull tab.

According to our invention, after making provision for sufiicient metalin the tongues from which the cams are to be formed, the folded overtongues are subjected to a lateral swaging operation which produces asolid body of metal which is of sufficient height and length for thecam, and at the same time is supported by direct contact with the bodyof the pull tab throughout the length of the cam. Obviously this resultsin a cam which will withstand much greater pressure than those of thecam locks described above.

The detailed nature of the improvement and the method by which it isaccomplished will be apparent from the following description taken inconjunction with the accompanying drawings in which:

Fig. 1 is a perspective view of a zipper slider having a pull tabembodying our invention attached thereto and shown in unlocked position.

'or lug 15 to which a pull tab'16 is attached for operating the slider.The pull tab 16 is formed with a pair of identical cams 17 that areadapted to extend through the slots 14 when the pull tab is'in lockedposition as shown in Fig. 2 and pressed against the adjacent surface ofthe zipper elements 18 on a stringer 19 of the conventional type.,Theinner surface of the lower wing is formed with a depression 20 intowhich the elements 18 are forced to lock the slider against movement onthe stringers. V

The particular construction forming the cams 17 on the pull tab formsthe subject of this invention. One of the first stages in themanufacture of the pull tab is to stamp out the blank 16a as shown inFig. 3 wherein at one. end of the blank 16a is a half round opening 21for convenience in operating the tab. The opposite end of the blank 16ais bifurcated because of the polygonal shaped opening 22 and slot 23extending through the end of the blank 16a, the shape of the opening 22and the slot 23. being of such character as to provide ina wardlydirected opposedtrunnions 24. The blank 16a is formed with integraltongues 25 extending from the end of said blank on opposite sides of theslot 23, the inner edges 26 of the lugs being diverging relative to thelongitudinal axis of said blank. The outside edges 27 of said tongues 25are in line with the longitudinal edges of said blank except for thecutout recesses 28.

The next step of the operation is shown in Fig. 4 where the tongues 25are bent over to lie adjacent the upper surface of the blank with thetongue ends positioned relatively close to or in contact with saidsurface. It is to be noted that in bending the tongues 25 from theposition shown in Fig. 3 to the position shown in Fig. 4, the outeredges 27 will remain in a plane common with the outer edges of the blank16a.

The manner in which the tongues 25 are reformed to provide the solidcams is shown in Figs. 6 and 7. In this step the blank 16a, as shown inthe Fig. 4 state, is conveyed to a support plate 30, and an anvil block31 is positioned between the adjacent surfaces 26 of the tongues 25. Apair of swaging tools 32 are suitably mounted to reciprocally slide fromopposite sides of the blank 16a in direct line with the tongues 25. Theleading end of the tools 32 has a blunt face 33 and a pro jection 34having a tapered edge surface on all sides except the bottom of about 15degrees. The upper edge of the projection is inclined lengthwise thereofon an angle substantially comparable to the position that the camsassume when formed as shown in Fig. 4 and this upper edge reaches up toabout one-half the thickness of said tongues. During the swagingoperation it is necessary to confine the outer surfaces of the tongues25. For this purpose die members 35 are provided that descend againstthe top of the pull tab 16 along with the anvil block 31. Each diemember is formed with a transverse recess 36 shaped' to conform to thecam 17 and it is within this recess that the swaging tool 32reciprocates during the swaging operation.

As the tools 32 operate on their inward stroke the projection 34 firststrikes against a portion of the outer edges of the wall 27 and swagethe contacted portion inwardly. Also the blunt face 33 of the tools 32will abut the remaining faces of the edges 27 that are not contacted bythe tool projection 34 and force the remaining portion of said edges 27inwardly toa position substantially fiush with the base of the cutoutrecess 28. All the stock of the lugs that is forced inwardly by the endprojection 34 as well as the blunt edge'33 of the swaging tools 32 willbe drifted downward toward the adjacent surface of the blank 16a andproduce a reenforcing wall 37. The stock that is drifted by the swagingoperation is sufiicient to close up the space between the cams 17 andblank 16a and cause the wall 37 to lie in direct contact with theadjacent surface of the blank 16a.

During the lateral swaging operation the wide portions of the bent-overtongues are reduced to provide cams 17 of uniform width which are setinwardly from the side edge of the pull tab. Thus, in the reverseposition of the pull tab there is a solid portion of the tab adjacenteach cam that is in supporting contact with the slider body.

It will be observed although the cams are long enough to extend asubstantial distance to each side of said trunnions they taper somewhattoward their inner ends so that the high point of each cam is slightlybeyond the trunnions. This insures that the pull tab will notaccidentally kick out of locked position.

Afater the swaging operation the ends of the blank 16a on opposite sidesof the opening 22 and slot 23 including the trunnions 24 and the lugs 25are spread apart to the position as shown in Fig. 8 for convenience inassembling the pull tab to the bail of the slider 10.

It will be obvious that the reenforcing walls 37 will support the lugs25 to prevent them from being crushed out of their normal positionespecially when the pull tab is in an unlocked position as shown indotted outline in Fig. 2 and is subjected to any abnormal crushingforce.

We claim:

1. A cam lock slider for zipper fasteners, a rectangular flat metal pulltab comprising a body portion having a central aperture adjacent one endso as to provide bifurcations at that end, each bifurcation having aninwardly extending trunnion by which the pull tab may be pivotallyattached to a slider, at least one of said bifurcations having alongitudinal extension adjacent said end which has a U-bend beyond thebody portion of the pull tab and which extension when bent, underliesthe body portion of the pull. tab on one side of said aperture, saidextension projecting inwardly beyond the U-bend a substantial distancealong the underside of the pull tab to form a locking cam whose heightis substantially greater than the thickness of the metal of the pulltab, such cam having a laterally outwardly opening recess and a solidweb of metal in supporting contact with the pull tab throughout thelength of that portion of such cam which extends inwardly from theU-bend, such laterally opening recess and solid web of metal resultingfrom transverse swaging of the metal of said extension which underliesthe pull tab.

2. A cam lock slider as set forth in claim 1 wherein each bifurcationhas a longitudinal extension as recited and a cam as recited whereineach cam is located inwardly from the adjacent sides of the pull tabthroughout the cam length.

3. A cam lock slider for zipper fasteners according to claim 1 whereinthe cam is long enough to extend a substantial distance to each side ofthe adjacent trunnion, said cam tapering somewhat toward its inner endso that the high point of the cam is slightly beyond the said adjacenttrunnion.

References Cited in the file of this patent UNITED STATES PATENTS440,240 Honk Nov. 11, 1890 1,381,311 Johnson et al June 14, 19211,475,720 Prentice Nov. 27, 1923 1,991,831 Winterhalter Feb. 19, 19352,193,080 Soave Mar. 12, 1940 2,364,100 Savitzky Dec. 5, 1944 2,384,145Voity et al. Sept. 4, 1945 2,539,520 Mikulas Jan. 30, 1951 2,723,446Lawson Nov. 15, 1955 FOREIGN PATENTS 30,238 Switzerland Jan. 14, 1904

